Six or seven years ago, when a friend of mine was being threatened by an ex-boyfriend, I wrote to her MP and the police. I was worried that the verbal threats and harassment (smashing plant pots against her front door, that sort of thing) would escalate to physical violence. No one replied to my letters and even when my friend showed the police a court order she'd got in an attempt to stop the man stalking her, they said they couldn't do anything because it was "six of one and half a dozen of the other". In the end, she had no choice but to move to another part of London.

For years, victims of domestic violence have had to struggle against myths, not least the idea that they bring it on themselves by returning to violent men or refusing to give evidence against them. In fact, women are at greatest risk when they leave a violent man and there are numerous cases where a woman has repeatedly asked for help and been murdered within days. The Independent Police Complaints Commission is currently investigating the case of Katie Summers, a young mother who was stabbed to death by her ex-boyfriend in October last year, despite calling Greater Manchester police four times in the days before her murder. Last week the ex-partner, Brian Taylor, was imprisoned for life for killing her.

The point I'm making is that plenty of women already know they're at risk of domestic violence and they don't get the help they desperately need. That's why Jacqui Smith's latest idea, announced as part of a consultation to tackle violence against women, is that the police should alert women who fall in love with violent men. This strikes me as diversionary, if not actually dangerous. There's an obvious risk of making a mistake, mixing up similar names and alarming a woman unnecessarily, but there's also the question of what she is supposed to do with the information. Confront him and risk a beating? Seek protection from the police, even if the relationship is in the early stages and no crime has yet been committed?

And if the woman doesn't act, if she convinces herself that it's all a mistake or things will be different this time, what reaction will she get when she's beaten and bloodied and finally reports him? In a culture where blaming the victim is a popular blood sport – just think of the pop star Rhianna, or women who've been raped – it's more than likely that she will find herself criticised for not getting out sooner.

Some of the government's initiatives on domestic violence are to be welcomed, but this one strikes me as a headline-grabbing gimmick. There is still too much scepticism about the existence and scale of domestic violence, with a new government survey showing that one in five people believe it's OK to slap a wife or girlfriend. (The deniers will no doubt be out in force in response to this article, playing down violence against women and wrongly accusing me of not recognising that some men are victims as well.)

Like rape, the problem with domestic violence is that too many people still think it's trivial or the victim's fault, so that women find themselves accused of exaggerating their injuries or bringing violence on themselves. Vulnerable women are being failed by the authorities, and the last thing we need is a government policy which shifts responsibility on to victims and away from the people who are supposed to protect them.